Dear Bill, For our new terrace, we are looking for a shade tree that has the following characteristics:

• Moderate to fast growing.

• Canopy to provide shade for an 18-foot area within five years or so.

• Deciduous.

• Brilliant red (not plum or wine) fall color.

So far, we are focusing on the Pistache and ‘Red Sunset’ maple.

What do you think?

A.B.

 

Dear A.B.,

The best tree that comes to mind, off-the-bat, is trident maple (Acer buergerianum). It’s becoming a well-known street tree in Napa. Still, the fall color is variable.

Your ‘Red Sunset’ maple, which is a good choice for your situation, is “brilliant orange-red” as described in a grower’s catalogue I checked. Pistache (Pistacia chinensis) is also a good choice, but a somewhat slower growing tree. The autumn color varies from yellow to orange and red.

Many characteristics warrant serious attention before autumn color. It would be a huge mistake, though not an uncommon one, to select a tree based on one desired quality.

One good resource for getting started is selectree.calpoly.edu, the Cal Poly State University Web site for tree selection. It lists five categories of “tree values” and gives the user the opportunity to play around and narrow down the choices, based on desired tree qualities. They include tree health, safety, environmental concerns, site conditions, leaf, flower and fruit qualities, tree height, growth rate, shape, wildlife habitat, landscape applications, pests and diseases.

Plugging in various values, I found that selectree came up with some useful suggestions, e.g. ‘October Glory’ red maple, which is probably better suited to our climate than its close relative ‘Red Sunset’. Chinese Zelkova was another; a good tree that has not received much attention lately. Selectree didn’t mention trident maple until I did a specific search for that tree, and it recommended a few that I would not recommend in your situation (Liquidambar).

Autumn color in trees develops and changes throughout the fall season, and it changes from year to year, so choosing a tree for a preferred autumn color is inherently different from choosing a single paint color. It’s more like choosing a color scheme.

‘Red Sunset’ and ‘October Glory’ are cultivated varieties of the red maple species Acer rubrum. Also known as cultivars, c.v.’s, or clones, cultivated varieties are genetically identical plants. They are propagated from rooted cuttings, grafting, budding, or tissue culture. Being genetically identical, trees of a cutlivar will tend to have uniform autumn color if they are growing in similar conditions.

In contrast, Chinese Pistache trees, except for one rare c.v. ‘Keith Davey’ are grown from seed, so they are variable, like any other organism generated by sexual reproduction. Seedling trees within a species vary in many ways, including autumn color.  

Environment plays a huge role in fall color. The best color is brought on, not by frost, but shorter days, cooler temperatures and slight drought stress. Annual variations are reflected in the autumn colors.

Regarding color per se, we might occasionally see a primary red autumn leaf color, but we usually see red blended with other colors in the spectrum or color wheel.

On the yellow side of red, there are colors like crimson, carmine, mandarin and scarlet. Moving from red toward blue we see colors like wine, garnet, ruby, cardinal and blood red.

Some trees stay on the yellow side in fall. Ginkgo is one of the best for consistent, clear, bright yellow-gold. On the other side, the flowering pears tend toward deep reddish purple.

Today I picked a few leaves from an ‘October Glory’ red maple and compared them to a color chart. I found that one tree has leaves ranging from deep maroon and garnet, to scarlet with some hints of yellow and green. And the colors are changing daily.  

For some help finding samples of my recommended trident maple in town, I called Rob Hansen, the City of Napa’s tree care supervisor (rhansen@cityof napa.org). He directed me to the 2700 block of Iowa Street and the other  “state” streets around Foster Road. Many of the trident maples are doing well after about 5 years in the ground, but the colors are not developing so well for a tree species that is famous for brilliant fall color. Perhaps it will improve as autumn progresses, or maybe next year.

For the ‘Red Sunset’ maple, the best local spot I can think of is Meadowcreek Drive (off Starr and Pope Streets) in St. Helena. They’re growing in most of the front yards.

 This is a great time to select a tree for fall color. Take a walk or a drive, or just go to the nursery and have a look!

Bill Pramuk is a registered consulting arborist. Visit his Web site, www.billpramuk.com, e-mail questions to info@billpramuk.com or call (707) 226-2884.)